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DIAMONDS AND OPALS AND PEARLS—OH MY! September 07, 2010 (0 comments)


Carlsbad, CA--Gem lovers, take note: GIA’s Summer 2010 issue of Gems & Gemology features a comparison of two of the world’s most important blue diamonds, new sources of opal, and cutting-edge technology for pearl identification, plus interesting developments in synthetic and HPHT-treated diamonds.

Dr. Eloise Gaillou and colleagues describe how they tested the famed Wittelsbach-Graff and Hope diamonds to determine whether they came from the same piece of rough. Because both diamonds have similar color and long-lasting phosphorescence and believed to have been purchased in India during the 17th century, there has been widespread speculation that they were cut from the same crystal. But new observations and tests show they do not share a common parent.

Opal lovers will enjoy an article by Dr. Benjamin Rondeau, who with coauthors describes attractive play-of-color opal from Wegel Tena, in Ethiopia’s Wollo Province. Discovered in 2008, the deposit has produced mainly white opal, with some brown, fire, and colorless opal. Most appears to be resistant to crazing.

Two articles explore X-ray computed microtomography in pearl identification. Highlights from the “Lab Notes” section include a Fancy Vivid blue HPHT-treated diamond, a near-colorless CVD-grown synthetic diamond larger than one carat, and a green beryllium-diffused sapphire, while other articles explore new gem finds and more.

For more information, call Martha Rivera, toll-free, (800) 421-7250, ext. 7142. From outside the U.S. and Canada, call (760) 603-4000, ext. 7142. To purchase PDF versions of specific articles or sections, visit

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